Patterned media, which have tracks in which a plurality of magnetic bit-cells that are isolated magnetically from each other are aligned in a periodically repeating array, have recently received attention as potential magnetic-recording media for hard-disk drives (HDDs). The patterned media are advantageous in that adjacent track interference (ATI) and transition noise due to the transitions between recorded bits can be reduced, and thermal decay of recorded magnetization in recorded bits can be suppressed. When data is written onto the patterned medium, a magnetic-recording field is applied that is timed to correspond with the alignment pitches of the magnetic hit-cells. The timing of the magnetic-recording field is adjusted based on data read from the tracks before data is written.
However, data can not be correctly read from the tracks during the writing of data due to the presence of the magnetic-recording field. Thus, when the alignment pitches of the magnetic bit-cells and the timing of the magnetic-recording field are shifted from each other due to variation of the rotation speed of a spindle motor and the frequency of a write-clock signal causes a failure in the writing of data, such a failure may not be recognized. One method for recognizing success, or failure, in the writing of data is to utilize a verification process for confirming whether, or not, data can be correctly read from a portion of a magnetic-recording disk where the data is written after the writing of data. If the verification process is performed every time the data is written, performance of the HOD may be impaired.